This study of the relationship between female employment and fertility is based on a survey of 1000 ever-married women in Karachi. A distinct pattern of differentials in actual performance and in desired fertility is observed across working and non-working women. Working women are not a homogeneous group, and the differences across six broad occupational groups of working women are more marked than those between working and non-working women. Women in higher status occupations marry much later than and have half the completed family size of – those women working in lower status occupations. The fertility of non-working women lies somewhere in between these two groups. Some reasons for the fertility differentials found are identified in variations in point of entry into the labour force relative to the stage in child-bearing, in expectations from sons in old age support, and in relative facility in seeking means of fertility control. Working women in higher status occupations also have better chances of their children surviving, whereas women in lower status occupations suffer a greater toll of child deaths.